The overall objective is to further develop neoplastic and phenotypic marker probes amenable to flow cytometric (FCM) analysis, in order to advance objectivity, accuracy and scope of information pertaining to tumor cell heterogeneity, for better diagnosis and prognosis of human malignant disease. As an alternative marker for DNA-diploid disease, DS-RNA content will be further explored. DNARNA investigation will be continued to study the malignant lymphomas in terms of classification and prognostic implications. An FCM assay for estrogen receptor analysis will be developed, using both FITC-conjugated estradiol and monoclonal antibodies against the receptor protein. When coupled with DNA content analysis, this will allow to probe the heterogeneity of human breast cancer in terms of ploidy, cell cycle kinetics and CR expression.